Method for increasing yields of light oil and total liquid products, promoting the combustion of CO and reducing NOx emission in flue gas in the petroleum refining FCC process and the improved FCC catalyst

ABSTRACT

The present invention relates to non-noble metal catalyst comprising Cu—Al/Ce—Al complex oxides and aluminum oxide support. The catalysts comprise Ce—Al complex oxide and Cu—Al complex oxide successively loaded on the aluminum oxide support, wherein the loading weight ratio is 0.02-0.10 for Ce—Al—O/Al 2 O 3  and 0.05-0.15 for Cu—Al—O/Al 2 O 3 , and the Cu—Al complex oxide is dispersed in cluster form on the surface of the aluminum oxide support pre-covered with high dispersed nanoparticles of the Ce—Al complex oxide. Furthermore, the present invention relates to a process for preparing the catalysts, their use as FCC process additive with high catalytic activity, high hydrothermal stability and ability of promoting CO combustion and reducing NOx exhaust and increasing yields of light oil and total liquid products in the improved FCC process of petroleum refining and the improved FCC catalyst which is obtained after treatment in the presence of said FCC process additive.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part application of U.S. patent application Ser. No.09/826,174.

TECHNICAL FIELD

[0002] The present invention relates to non-noble metal combustion catalysts comprising copper-aluminum/cerium-aluminum complex oxides and aluminum oxide support heir preparation and use in the Fluid Catalytic Cracking process (FCC) of the petroleum refining as a kind of FCC process additive. More particularly, the present invention relates to non-noble metal catalysts comprising copper-aluminum complex oxide uniformly dispersed in cluster form on the aluminum oxide support pre-covered with highly dispersed microcrystals of Ce—Al complex oxide, a process for their preparation and their use in the FCC process of petroleum refining as a FCC process additive with high catalytic activity, high hydrothermal stability and the abilities of promoting the combustion of CO and/or reducing the emission of NOx, and/or also, increasing the yields of LO (light oil) and total liquid products. The present invention also relates to an improved FCC catalyst, which is obtained after treatment in the presence of said FCC process additive.

BACKGROUND ART

[0003] In the FCC process of petroleum refining, the catalysts for catalytic cracking used in a vast amount usually need to be regenerated by the aid of the combustion catalysts for carbon monoxide to strengthen carbon combustion of spent catalysts, fully combusting CO in the system and to make the FCC plant processing steadily. Up to now, the combustion catalysts for carbon monoxide widely used in the art all have noble metals of VIII group, such as Pt, Pd, etc, as their active component. It means Pt combustion catalysts for carbon monoxide is used in the FCC process worldwide. In order to solve the problems of noble metal shortage and high production cost, non-noble metal carbon monoxide combustion catalysts, including perovskite-type complex oxides and non-perovskite type oxides, have been developed to substitute for all or part of noble metal (CN 1022542C and CN 1072109A, etc.). However, for these non-noble metal catalysts, neither their catalytic activity and stability, nor the reliability and facility of the related process, can be comparable to that achieved by using noble metal catalysts. For instance, the catalysts usually become inactive at the high temperature used in hydrothermal condition due to agglomeration of the active components and inevitable by-products. In addition; it came from the practice those Pt combustion catalysts for carbon monoxide contributes to combustion result, but increasing the emission of NOx in flue gas. It not only contaminates the environment, but also corrodes the equipment in FCCU (FCC Unit). Therefore, researchers in the art have been making great efforts to improve the performances of the non-noble metal combustion catalysts. Since FCC is important petroleum refining process for lightening heavy oil, producing gasoline, diesel and LPG (liquid petroleum gas), improving FCC technique for upgrading heavy oil to increase yield of total liquid products (Light Oil+LPG), especially yield of Light Oil is the most interesting project in this field.

[0004] The present inventors have developed two kinds of suitable complex oxides with imperfect structure on the bases of the structural chemistry principles. The interactions between two complex oxides make it possible for the catalytic active component to be uniformly dispersed on and firmly combined with the support, and thereby a FCC process additive having good performance and meeting the demands of FCC process have been prepared, showing a new progress in the art.

DISCLOSURE OF THE INVENTION

[0005] Therefore, an object of the present invention is to provide catalysts comprising non-noble metal complex oxides firmly combined with a support as catalytic component, which have high CO combustion-promoting catalytic activity, high hydrothermal stability, and hence can be used to substitute for noble metal combustion catalysts for carbon monoxide. The catalyst of the present invention also has favorable effects in increasing the yields of LO and totals liquid products, reducing the NOx exhaust and the contamination to the environment and thus can be used as a FCC process additive. It is also an object of the present invention to provide a process for preparing the additives as described above. Another object of the present invention relates to the use of the non-noble metal additives as carbon monoxide combustion catalysts and reducing NOx emission in flue gas in the FCC process. Not only using the catalysts of present invention to increase the yields of total liquid products and LO in heavy oil FCC process, but also to reduce NO_(x) emission in flue gas and provide improved FCC catalysts obtained after treatment in the presence of the additive as described above are objects of the present invention. Other objects of the present invention will be embodied in the following detailed description of the present invention.

[0006] FCC catalysts usually consist of Y type zeolite as active component and Silicon Oxides, Aluminum Oxides or Si—Al complex Oxides as matrix.

[0007] The present invention relates to non-noble metal combustion catalysts comprising cerium-aluminum and copper-aluminum complex oxides successively loaded on aluminum oxide support, wherein the weight ratio between the two loaded complex oxides and the aluminum oxide support is respectively from 0.02 to 0.10, preferably 0.04-0.06 for Ce—Al complex oxide and 0.05-0.15, preferably 0.08-0.11 for Cu—Al complex oxide. Preferably, the Ce—Al complex oxide covering the surface of the aluminum oxide support is in the form of nanometer microcrystals with an imperfect structure, having a general formula of [Ce_(1−y)Al_(y)][O_(2−y/2)□_(y/2)][I]; and the Cu—Al complex oxide is dispersed in cluster form on the microcrystals of the Ce—Al complex oxide covering the aluminum oxide support, having an imperfect structure and a general formula of [Cu_(1-3x/2)Al_(x)□_(x/2)]O[II]; wherein x=0.05-0.23, preferably x=0.10-0.17; and y=0.05-0.30, preferably y=0.10-0.22; □ presents the vacancy in the crystal structure.

[0008] The present invention further relates to a process for preparing the aforesaid catalysts, which comprises:

[0009] A. impregnating the aluminum oxide support with an aqueous solution formed by mixing an aqueous solution comprising Ce—Al compounds, preferably Ce and Al salts, such as their nitrates, with citric acid or its aqueous solution in a citric acid/total Ce—Al metal ions molar ratio of 0.3-1.0, then the impregnated support being baked at 100-140° C. for 2-4 hours, pyrolyzed at 200-300° C. for 2-3 hrs, and then activated at 600-750° C. for 2-5 hrs, to obtain the solid Al₂O₃ Support covered with microcrystals of Ce—Al complex oxides; And

[0010] B. impregnating the solid obtained in the step A in an aqueous solution formed by mixing an aqueous solution comprising Cu—Al compounds, preferably Cu and Al salts, such as their nitrates, with citric acid or its aqueous solution in a citric/total Cu—Al metal ions molar ratio of 0.3-1.0, then the impregnated solid being baked at 100-150° C. for 2-4 hrs, pyrolyzted at 200-300° C. for 2-3 hrs, and then activated at 500-650° C. for 2-3 hrs, to obtain the final catalyst which further comprises Cu—Al complex oxide dispersed on its surface pre-covered with tie microcrystals of Ce—Al complex oxide.

[0011] The present invention also relates to the use of the aforesaid catalysts as FCC process additive being able to promote the combustion of CO and reduce emission of NOx in flue gas in FCC process of petroleum refining. More particularly, the present invention relates to the use of the aforesaid catalysts increasing total liquid products yield (LO+LPG), especially LO yield in heavy oil FCC process, also relates to the improved FCC catalysts obtained after treatment in the presence of the aforesaid FCC process additive.

BRIEF DESCRIPTION OF DRAWINGS

[0012]FIG. 1 is an XRD pattern of Ce—Al—O/γ-Al₂O₃;

[0013]FIG. 2 is an XRD pattern of CeO₂/γ-Al₂O₃;

[0014]FIG. 3 is an XRD pattern of CeO₂;

[0015]FIG. 4 is an XRD pattern of Ce—Al—O;

[0016]FIG. 5 is an XRD pattern of Cu—Al—O/Ce—Al—O/γ-Al₂O₃;

[0017]FIG. 6 is an XRD pattern of CuO/CeO₂/γ-Al₂O₃;

BEST MODE FOR CARRYING OUT THE INVENTION

[0018] The study on the combustion catalysts for carbon monoxide formed by loading non-noble metal oxides, such as oxides of Cu, Co, Mn, Ce and rare earth or alkaline earth metals, as active components on various supports to substitute for all or part of noble-metal combustion catalysts has been carried out for many years in the art, and a variety of products have been made. However, the products which actually meet the requirements of having high activity, high mechanical strength and long service life concurrently, and hence can be used to substitute for the noble metal catalysts currently used in industry, are seldom seen. It should be noticed that, these products generally have a relatively high initial activity as combustion catalyst, but the hydrothermal stability, which relates to the service life is usually low, while the hydrothermal stability under the circumstance surrounded by the FCC catalysts is most hard to come by. Moreover, the catalysts must meet a series of requirements for production in industrial scale, which include that the preparing process must be simple, and the raw materials must be widely available and inexpensive. Based on an intensive study for many years, the present inventors have developed novel catalysts, which meet the aforesaid requirements.

[0019] Most surprisingly, the aforesaid non-noble catalysts of the present invention being used as additives in FCC process are not only promoting the combustion of CO, increasing regenerating efficiency of spent catalysts and reducing emission of NOx in flue gas, but also having the unexpected effect on increasing the yield of LO and total liquid products. The increasing yield of LO can be over 1% comparing with commonly used noble metal CO combustion catalysts, This perhaps is because in the high temperature and hydrothermal circumstances of regenerator, the catalysts of present invention not only have the function of catalytic redox, but also have the function of modification for Y type zeolite of FCC catalysts. Modified Y type zeolite accordingly adjusts reaction character related to acidity and which leads to the result that regenerated FCC catalysts decrease second cracking reaction to LO when entering the riser of the reactor, therefore increase yields of LO and total liquid products.

[0020] The present invention relates to non-noble metal catalysts, which are used as additives in FCC process, comprising copper-aluminum/cerium-aluminum complex oxides successively loaded on aluminum oxide support, with a loading weight ratio of 0.02-0.10, preferably 0.04-0,06, for Ce—Al—O/Al₂O₃; and 0.05-0.15, preferably 0.08-0.11, for Cu—Al—O/Al₂O₃. The supports used are generally native or synthesized solid materials of aluminum oxide, including the metastable type of aluminum oxide with a mesophase, such as γ-Al₂O₃.

[0021] As active component of the catalysts of the present invention, the Ce—Al complex oxide and Cu—Al complex oxide are fixed on the support surface in the form of nanoparticles. In terms of the results of X-ray diffraction, the Ce—Al complex oxide can be expressed as an imperfect structure having the following formula [I]

[Ce_(1−y)Al_(y)][O_(2−y/2)□_(y/2)]  [I]

[0022] wherein y=0.05-0.30, preferably y=0.10-0.22, and □ represents the vacancy in the structure; the Cu—Al complex oxide can be expressed as an imperfect structure having the following formula [II]

[Cu_(1-3x/2)Al_(x)□_(x/2)]O   [II]

[0023] wherein x=0.05-0.23, preferably x=0.10-0.17; and □ represents the vacancy in the structure.

[0024] As used here, the abbreviation “Ce—Al—O” means a Ce—Al complex oxide having Ce, Al and O as its main components; and “Cu—Al—O” means a Cu—Al complex oxide having Cu, Al and O as its main components.

[0025] Since the Ce—Al complex oxide is possessed of the imperfect structure, the interaction of the metastable type of aluminum oxide with the Ce—Al complex oxide must be stronger than that with CeO₂, and hence the Ce—Al complex oxide can be loaded on the γ-Al₂O₃ support in a high-dispersed form. On the other hand, since a strong interaction exists between the aforesaid Ce—Al and Cu—Al complex oxides, the Cu—Al complex oxide will be almost totally attached to the Ce—Al complex oxide and scarcely contact with γ-Al₂O₃ when the Cu—Al complex oxide is loaded on the Al₂O₃ support pre-covered with the microcrystals of Ce—Al complex oxide, and hence reducing effectively the destruction probability of the active components due to the interaction between the Cu ions in the active components and the Al ions in the aluminum oxide support. Therefore, the Ce—Al complex oxide and Cu—Al complex oxide of the present invention can be successively and directly loaded on the aluminum oxide support as active components, being able to exert their catalytic effect stably at the high temperature of hydrothermal condition. Furthermore, the Ce—Al complex oxide covering the surface of the aluminum oxide support is preferably in the form of microcrystals, particularly in the form of nanoparticules with a size less than 10 nanometers; also preferred is that the Cu—Al complex oxide is dispersed in cluster form on the aluminum oxide support pre-covered with the microcrystals of the Ce—Al complex oxide.

[0026] The process for preparing the catalysts of the present invention comprises:

[0027] A. Impregnating the aluminum oxide support is in a mixed solution formed by mixing an aqueous solution comprising Ce, Al compound with citric acid or its aqueous solution, and the impregnated support being baked at 100-140° C. for 2-4 hrs., pyrolyzed at 200-300° C. for 2-3 hrs, and then activated at 600-750° C. for 2-5 hrs, to obtain the solid aluminum oxide support covered with microcrystals of Ce—Al complex oxide; and

[0028] B. Impregnating the solid obtained in the aforesaid step A in a mixed solution formed by mixing an aqueous solution comprising Cu, Al compound with citric acid or its aqueous solution, and the impregnated support being baked at 100-150° C. for 2-4 hrs, pyrolyzed at 200-300° C. for 2-3 hrs, and then activated at 500-650° C. for 2-3 hrs, to obtain the final catalyst which further comprises Cu—Al complex oxide dispersed on its surface pre-covered with the microcrystals of the Ce—Al complex oxide.

[0029] The Cu, Al, and Ce compounds used in the process of the present invention are generally water-soluble, and can be their salts, such as copper nitrate, aluminum nitrate and cerous nitrate etc. They can be used in the form of solution, preferably in the form of aqueous solution with concentrations of 0.50-4.00 mol/L, preferably 2.00-3.50 mol/L for Cu compound; 1.00-2.20 mol/L, preferably 1.50-2.00 mol/L for Al compound; 0.50-4.00 mol/L, preferably 1.00-2.00 mol/L for Ce compound. The citric acid can be used directly or in the form of its aqueous solution. In general, the citric acid or its aqueous solution is mixed uniformly with the aqueous solutions of Ce and Al compounds or Cu and Al compounds, respectively, in a citric acid/total metal ions molar ratio of 0.3-1.0, preferably 0.4-0.8, to obtain their complex solution.

[0030] The aluminum oxide support used in the present invention can be of the metastable type alumna, for example, γ-Al₂O₃. In general, it is preferred that the support of the CO combustion catalysts in the FCC process for petroleum refining is in microsphere form with a particle size of 10-200 μm, preferably 20-100 μm. In a preferred embodiment, 65-85 wt % of the support has a particle size of 40-80 μm, and the weight percentage of the support particles with a size larger than 80 μm is less than 20 wt %. Typically the support has a water-absorbility of 0.50-0.65 ml/g, preferably 0.55-0.60 ml/g.

[0031] In a specific embodiment of the present invention process, the catalysts were prepared according to the following preferred procedures. The following analysis and description are presented for illustrating the present invention, and are not intended to bond the present invention into a certain theory.

[0032] 1.The Loading of the Ce—Al Complex Oxide

[0033] An aqueous solution comprising cerous nitrate and aluminum nitrate in an appropriate molar ratio was prepared, and citric acid was added into the solution in a citric acid/total metal ions molar ratio of 0.3-1.0. After mixing uniformly to allow complexation reaction taking place, a part of the complex solution was taken as required to impregnate the γ-Al₂O₃ support. The impregnated Al₂O₃ support was baked at 100-140° C. for 2-4 hrs., pyrolyzed at 200-300° C. for 2-3 hrs, and then activated at 600-750° C. for 2-5 hrs. After cooling, the solid γ-Al₂O₃ covered with microcrystals of the Ce—Al complex oxide, Ce—Al—O/γ-Al₂O₃, was obtained, wherein the weigh ratio of the Ce—Al—O to γ-Al₂O₃ was 0.04-0.06. The γ-Al₂O₃ was in spherical form with a water-absorbility of 0.50-0.65 ml/g, in which 65-85 wt % of the γ-Al₂O₃ particles had a particle size of 40-80 μm, and less than 20 wt % of the γ-Al₂O₃ particles had a particle size larger than 80 μm. The X-ray diffraction pattern of the solid support prepared by the aforesaid method is shown in FIG. 1.

[0034] In the present invention, the Ce—Al—O complex oxide instead of CeO₂ was used, since the two oxides have different crystalline state.

[0035] To interpret this more clearly, the CeO₂/γ-Al₂O₃ was prepared by impregnating γ-Al₂O₃ in a cerous nitrate solution with a certain concentration (the weight ratio of the CeO₂ to γ-Al₂O₃ is 0.05) under the same process condition for loading the Ce—Al complex oxide. The XRD pattern of the product is shown in FIG. 2. Comparing FIG. 1 with FIG. 2, it is not difficult to find that the full width at half maximum intensity of the Ce—Al—O phase in FIG. 1 broadens obviously, indicating that the grain size of the Ce—Al—O dispersed on the surface of the γ-Al₂O₃ is smaller than that of CeO₂. To obtain a quantitative result, two samples of single phase of CeO₂ and Ce—Al—O without γ-Al₂O₃ support were prepared to avoid the interference of the X-ray diffuse scattering of the γ-Al₂O₃ on the XRD intensity measurement of the complex oxides.

[0036] The sample containing merely oxide of Ce (2#) was prepared by using cerous nitrate as staring material, and the sample of the complex oxide containing both of Ce and Al ions (3#) in a Ce/Al molar ratio of 8:1 was also prepared. Their XRD patterns are shown in FIG. 3 and FIG. 4, respectively.

[0037] It can be seen from FIG. 3 that the sample 2# is a pure phase of CeO₂. The background of the XRD diagram in FIG. 4 is normal, the interplanar distance d and the distribution of the diffraction intensity I are the same with those of CeO₂, and no γ-Al₂O₃ phase can be detected, implying that the most part of the Al³⁺ ions in the sample 3# have entered into the lattice of the CeO₂ and the Ce—Al complex oxide with a formula of [Ce_(1−y)Al_(y)][O_(2−y/2)□_(y/2)] and the structure of CeO₂ was formed. In terms of the X-ray peak broadening, the D₁₁₀ of the CeO₂ in sample 2# was determined to be 250 Å, while the D₁₁₀ of the Ce—Al—O in sample 3# was 75 Å, wherein D₁₁₀ represents the dimension of the grain in the 110 direction. The results indicate that the Ce—Al—O will cover the surface of the γ-Al₂O₃ in a high-dispersed form when it is loaded on the surface of the γ-Al₂O₃, and the bare part of the γ-Al₂O₃ surface relatively diminishes.

[0038] 2. The Preparation of Catalyst

[0039] An aqueous solution of Cu²⁺ and Al³⁺ nitrates in an appropriate molar ratio was prepared, to which citric acid was added in a citric acid/total metal ions molar ratio of 0.3-1.0, and then mixed uniformly to allow the complexation reaction taking place. A part of the complex solution was taken as required to impregnate the prepared Ce—Al—O/γ-Al₂O₃ solid. The impregnated solid was baked at 100-150° C. for 2-4 hrs., Pyrolyzed at 200-300° C. for 2-3 hrs, and then activated at 500-650° C. for 2-3 hrs. The final catalyst, Cu—Al—O/Ce—Al—O/γ-Al₂O₃, was obtained as spherical microparticles in black or black-gray after cooling (sample 1#, hereinafter). FIG. 5 shows its XRD pattern.

[0040] In order to examine the structure of the Cu—Al—O complex oxide, a complex oxide (sample 4#, hereinafter) containing Cu and Al in a Cu/Al molar ratio of 6.1 was prepared under the same condition for preparing the catalyst. The background of the sample's XRD pattern is normal and no Al₂O₃ phase can be detected. The analysis of the XRD pattern indicates that the sample 4# has the same structure but different lattice parameters with that of CuO, and shows a space group of C_(2h) ⁶-C2/c. The detail data are shown in Table 1. TABLE 1 The lattice parameters of the sample 4# and copper oxide Sample 4# CuO (JCPDS 5-661) a₀ (Å) 4.693 4.684 b₀ (Å) 3.429 3.425 c₀ (Å) 5.125 5.129 β₀ 99⁰ 26′ 99⁰28′ Cell volume V₀ (Å³) 81.365 81.159

[0041] It can be seen that the cell volume of the sample 4# is apparently larger than that of CuO, indicating that the Al³⁺ ions entered into the crystal lattice, and the Cu—Al complex oxide having the crystal structure of CuO and the formula of [Cu_(1-3x/2)Al_(x)□_(x/2)]O was formed.

[0042] In order to interpret the effect of introducing Al³⁺ ions into active components, CuO was loaded on the CeO₂/γ-Al₂O₃ support according to the condition for preparing catalysts, and the XRD pattern of the product (sample 5#) CuO/CeO₂/γ-Al₂O₃ is shown in FIG. 6. It can be seen from FIG. 6 that the diffraction peaks of the CuO are distinctive, indicating that the CuO in sample 5# is distributed on the surface of CeO₂/γ-Al₂O₃ in a form of large grain with a particle size of larger than 2000 Å. On the other hand, no diffraction peak of CuO can be found in the XRD pattern of the prepared sample 1# (FIG. 5), showing that the active component of the catalyst of the present invention, Cu—Al—O, is dispersed on the surface of Ce—Al—O/γ-Al₂O₃ in cluster form.

[0043] The sample 5# was evaluated after hydrothermal aging treatment under the condition of example 1(4)-b, the conversion of CO was determined to be 25%, and the hydrothermal stability was much lower than that of the sample 1#.

[0044] In order to reveal the interaction between the two complex oxides of Ce—Al—O and Cu—Al—O in the prepared catalysts, the values of the binding energy of Cu in the two systems were measured by using XPS.

[0045] In P. W. Park and J. S. Ledford, “The influence of surface structure on the catalytic activity of cerium promoted copper oxide catalysts on alumina: oxidation of carbon monoxide and methane”, Catalysis Letters, 50(1998) 41-48, the values of the Cu2P_(2/3) of both the CuO/γ-Al₂O₃ and CuO/CeO₂/γ-Al₂O₃ were reported to be 935.1 eV determined by using XPS (the value of Cu2P_(2/3) of the sample 5#, CuO/CeO₂/γ-Al₂O₃, prepared in the present invention is 935.2 eV, consistent with the literature value), while the binding energy of Cu in CuAl₂O₄ was 935.0 eV. The values of the binding energy of Cu in both samples of Coo/γ-Al₂O₃ and CuO/CeO₂/γ-Al₂O₃ are all consistent with that in CuAl₂O₄, demonstrating that the γ-Al₂O₃ has a certain influence on the binding energy of Cu which isn't weakened by the existence of CeO₂, and most part of Coo are attached on the γ-Al₂O_(3 whether) the surface of γ-Al₂O₃ are covered with CeO₂ or not.

[0046] The value of Cu2P_(2/3) of the prepared sample 1#, Cu—Al—O/Ce—Al—O/γ-Al₂O₃, was measured to be 933.90 eV by using XPS, which is different with that of both CuO/γ-Al₂O₃ and CuO/CeO₂/γ-Al₂O₃, but is consistent with the value of 933.9 eV for CuO, indicating that the γ-Al₂O₃ support in sample 1# has little influence on the binding energy of Cu in the active components. This is due to that the most part of active components was attached to the microcrystals of the Ce—Al—O complex oxide rather than the surface of γ-Al₂O₃.

[0047] Therefore, it can be concluded that there exist high-dispersed Cu—Al—O and high-dispersed Ce—Al—C in the catalysts of the present invention. The strong interaction between the two complex oxides having imperfect structure endows the catalysts with high activity as well as high hydrothermal stability, particularly the hydrothermal stability at high temperature under the circumstance surrounded by the FCC catalysts, showing obvious effects on promoting the combustion of CO, reducing NOx emission and/or increasing the yields of LO and total liquid products, and hence improving the use value of the products.

[0048] The following examples are carried out so as to firer illustrate the present invention, but they can not be conceived as limit to the scope of the invention.

EXAMPLES Example 1

[0049] γ-Al₂O₃ with a water-absorbility of 0.55 was used as support, in which the particles with a particle size in the range of 40-80 μm constituted 70 wt % of the total support weight, and the proportion of the particles with a particle size larger than 80 μm was less than 20 wt %.

[0050] The procedures for preparing and evaluating the catalysts are as followings:

[0051] (1) 66.8 ml of 2.00 mol/L aqueous solution of Ce(NO₃)₃ was mixed with 8.3 ml of 2.00 mol/L aqueous solution of Al(NO₃)₃, then 15.8 g of citric acid (C₆H₈O₇.H₂O) and 190.0 ml of water were added to allow the complexation reaction taking place. The complex solution was used to impregnate 500 g of the aforesaid γ-Al₂O₃ support. The resulting impregnated support was baked at 120° C. for 2 hrs., pyrolyzed at 280° C. for 2 hrs, and then activated at 680° C. for 3 hrs. After cooling, the solid of Ce—Al—O/γ-Al₂O₃ having the XRD pattern shown in FIG. 1 was obtained.

[0052] (2) 188.0 ml of 3.06 mol/L aqueous solution of Cu(NO₃)₂ and 43.1 ml of 2.14 mol/L aqueous solution of Al(NO₃)₃ were mixed, then 69.5 g of citric acid was added and mixed uniformly to allow the complexation reaction taking place. The complex solution was used to impregnate the above solid Ce—Al—O/γ-Al₂O₃, and the impregnated solid was baked at 110° C. for 3 hrs., pyrolyzed at 250° C. for 2.5 hrs, and then activated at 580° C. for 2 hrs, to obtain the catalyst Cu—Al—O/Ce—Al—O/γ-Al₂O₃. The product is referred to as sample 1#, and its XRD pattern is shown in FIG. 5

[0053] (3) Determination of CO Conversion

[0054] The catalysts of the present invention can be used to convert CO into CO₂. By mixing 1.0 g sample 1# with 59.0 g of γ-Al₂O₃, placing the mixture in a fixed fluidized bed reactor, and introducing the mixed reactant gas in which the concentrations of CO₂, CO and O₂ were 3.25 (v), 5.3% (v), and 2.9% (v), respectively, and the balance was N₂, the conversion of CO was determined to be 100% at 593° C. and a space velocity of 40,000/hr.

[0055] In the FCC regenerator, three following reactions exist simultaneously:

C+1/2O₂→CO

C+O₂→CO₂

CO+1/2O₂→CO₂

[0056] Since there always exists a certain partial pressure of CO₂ in the system, so the mixed reactant gas used in the evaluation test should contain an appropriate amount of CO₂ to simulate the ambient atmosphere in practical operation more closely.

[0057] (4) Evaluation of Hydrothermal Aging Test

[0058] a) Sample 1#

[0059] 8.0 g of sample 1# was weighted into a porcelain boat and heated in a tube heating furnace at 788° C. for 12 hrs under a mixed gas stream comprising 90% (v) of water vapor and 10% (v) of air at a space velocity of 15000/hr.

[0060] 1.0 g of the sample after being treated under the above hydrothermal condition was admixed with 59.0 g of γ-Al₂O₃, placed in a fixed fluidized bed reactor, and evaluated under the condition of (3). The conversion of CO was determined to be 96%.

[0061] b) Mixture of the Sample 1# and the Fresh FCC Catalyst

[0062] 2.0 g of the sample 1# was mixed with 6.0 g fresh FCC catalyst, and the mixture was treated under the hydrothermal condition of (4)-a). 4.0 g of the sample after hydrothermal treatment was mixed with 56.0 g of γ-Al₂O₃, and the mixture was placed in a fixed fluidized-bed reactor to be evaluated under the condition of (3). The conversion of CO was determined to be 64%.

[0063] c). Mixture of the Sample 1# and Deactivated FCC Catalyst

[0064] The FCC catalyst, which was attached with more or less deposition of carbon after FCC reaction and needed to be regenerated, is called deactivated FCC catalyst. The deactivated FCC catalyst used here was taken from the FCC unit without adding any combustion promoter, in which there no residual combustion promoter existed and its carbon content was about 1.0%.

[0065] Following the same manner as that of (4)-b), except that the 10% (v) of air in the mixed gas was replaced with N₂, and the fresh FCC catalyst was replaced with the deactivated FCC catalyst. The catalyst obtained after such hydrothermal treatment was evaluated under the condition described in (3), and the conversion of CO was determined to be 72%.

[0066] The combustion promoters used in industry are surrounded by a large amount of FCC catalyst during the practical operation. The test results demonstrate that the surface of the promoter was inevitably surrounded in the main components of the FCC catalysts, and the catalytic performance of the promoter will be destroyed gradually at the high temperature used in the hydrothermal treatment. This effect will be more serious in the fresh FCC catalyst than in the deactivated FCC catalyst. Therefore, the evaluation of the hydrothermal treatment using the mixture of the promoter sample with the fresh FCC catalyst and the deactivated FCC catalyst will be more close to the practical situation of the promoter in the FCC unit.

[0067] (5) Pilot Test (Simulate Commercial Operation Conditions)

[0068] In this comparative test, the sample 1# of the present invention and a conventional combustion promoter containing 500 ppm Pt were evaluated under the same condition. The pilot test was carried out on a small-sized FCC testing equipment with a riser. The FCC catalyst total inventory of the pilot plant was 4.0 Kg and the catalyst used was the regenerated LV-23 FCC catalyst manufactured by Catalyst Factory of Lanzhou Petro Chemical Co., China, which was taken from an FCC unit without adding any combustion promoter. Both amounts of sample 1# and conventional Pt combustion promoter are 3000 ppm, respectively. The oil feed was VGO containing 25% of China Daqing vacuum residuum. The operation condition is shown in Table 2. TABLE 2 The operation condition of FCC Pt combustion Pt combustion promoter Sample 1# promoter Sample 1# Reaction 510 510 regeneration 680 680 temperature temperature (° C.) (° C.) Reaction 0.115 0.115 temp. of 660 660 pressure regenerated (mol/LPa) catalyst (° C.) Flow rate of the 1.203 1.196 Preheating 280 280 oil feed Kg/hr) temp. of feed (° C.) Contact time(s) 2.08 2.07 temp. of mixing 520 520 feed/catalyst (° C.) Catalyst/oil 6.67 6.62 Combustion air 720 720 ratio rate (L/hr)

[0069] TABLE 3 The composition of the flue gas Pt combustion promoter Sample 1# O₂ (% vol) 2.12 2.24 CO (% vol) 0.22 0.26 NO_(x) (ppm) 723 371

[0070] The data demonstrate that the sample 1# possesses the combustion-promoting effect comparable with that of the Pt combustion promoter, and has the advantage of reducing the NO_(x) in the flue gas by 50%, being favorable to the air cleaning and reducing the acid corrosion of the equipment.

Example 2

[0071] (1) 67.9 ml of 2.00 mol/L aqueous solution of Ce(NO₃)₃ was mixed with 5.1 ml of 2.00 mol/L aqueous solution of Al(NO₃)₃, then 15.3 g of citric acid and 192.5 ml of water were added to allow the complexation reaction taking place. The complex solution was used to impregnate 500 g of the support used in Example 1. The resulting impregnated support was baked, pyrolyzed and activated under the conditions described in step (1) of the Example 1 to obtain the solid of Ce—Al—O/γ-Al₂O₃-a.

[0072] (2) 195.4 ml of 3.06 mol/L aqueous solution of Cu(NO₃)₂ and 21.9 ml of 2.14 mol/L aqueous solution of Al(NO₃)₃ were mixed, then 67.8 g of citric acid and 15.7 ml of water were added and mixed uniformly to allow the complexation reaction taking place The complex solution was used to impregnate the above solid of Ce—Al—O/γ-Al₂O₃-a, and the impregnated solid was baked, pyrolyzed and activated under the condition described in step (2) of the Example 1 to obtain the catalyst.

[0073] (3) The obtained catalyst was evaluated following the manner described in Example 1(3), and the conversion of CO was determined to be 96% After hydrothermal aging treatment under the condition described in Example 1(4)-b), the conversion of CO was determined to be 51%.

Example 3

[0074] (1) 57.3 ml of 2.20 mol/L aqueous solution of Ce(NO₃)₃ was mixed with 21.0 ml of 2.00 mol/L aqueous solution of Al(NO₃)₃, then 17.6 g of citric acid and 185.8 ml of water were added to allow the complexation reaction taking place. The complex solution was used to impregnate 500 g of the support used in Example 1. The resulting impregnated support was baked, pyrolyzed and activated under the condition described in step (1) of the Example 1 to obtain the solid of Ce—Al—O/γ-Al₂O₃-b.

[0075] (2) 151.6 ml of 3.51 mol/L aqueous solution of Cu(NO₃)₂ and 71.2 ml of 2.14 mol/L aqueous solution of Al(NO₃)₃ were mixed, then 71.8 g of citric acid and 7.7 ml of water were added to allow the complexation reaction taking place. The complex solution was used to impregnate the above solid of Ce—Al—O /γ-Al₂O₃-b, and the impregnated solid was baked at 100° C. for 3 hrs, pyrolyzed at 270° C. for 2 hrs, and activated at 600° C. for 2 hrs to obtain the catalyst.

[0076] The catalyst was evaluated following the manner described in Example 2(3), and the conversion of CO was determined to be 93% and 54%, respectively.

Example 4

[0077] (1) 28.4 ml of 2.00 mol/L aqueous solution of Ce(NO₃)₃ was mixed with 2.1 ml of 2.00 mol/L aqueous solution of Al(NO₃)₃, then 6.4 g of citric acid and 240.0 ml of water were added to allow the complexation reaction taking place. The complex solution was used to impregnate 500 g of the support used in Example 1. The resulting impregnated support was baked at 140° C. for 1.5 hrs, pyrolyzed at 300° C. for 2 hrs, and activated at 700° C. for 2 hrs, to obtain the solid of Ce—Al—O/γ-Al₂O₃-c.

[0078] (2) 75.8 ml of 3.51 mol/L aqueous solution of Cu(NO₃)₂ and 35.6 ml of 2.14 mol/L aqueous solution of Al complex oxide is dispersed in cluster form on the aluminum oxide support, wherein the support is pre-covered with the particles of Ce—Al complex oxide were mixed, then 35.9 g of citric acid and 141.6 ml of water were added to allow the complexation reaction taking place. The complex solution was used to impregnate the above solid of Ce—Al—O /γ-Al₂O₃-c, and the impregnated solid was baked at 100° C. for 3 hrs, pyrolyzed at 220° C. for 3 hrs, and activated at 600° C. for 2.5 hrs to obtain the catalyst.

[0079] The catalyst was evaluated following the manner described in Example 2(3), and the CO conversions were determined to be 89% and 50%, respectively.

Example 5

[0080] The γ-Al₂O₃ with a water-absorbility of 0.62 ml/g was used as support, in which the particles with a size of 40-80 μm constituted of 70 wt % of the support, and the particles with a size larger than 80 μm is less than 15 wt %.

[0081] (1) 105.8 ml of 2.00 mol/L aqueous solution of Ce(NO₃)₃ was mixed with 35.2 ml of 2.00 mol/L aqueous solution of Al(NO₃)₃, then 29.6 g of citric acid and 118.4 ml of water were added to allow the complexation reaction taking place. The complex solution was used to impregnate 500 g of the above support, and the impregnated support was baked, pyrolyzed and activated under the condition described in Example 4(1) to obtain the solid of Ce—Al—O /γ-Al₂O₃-d.

[0082] (2) 219.9 ml of 3.81 mol/L aqueous solution of Cu(NO₃)₂ and 30.6 ml of 2.14 mol/L aqueous solution of Al(NO₃)₃ were mixed, then 94.8 g of citric acid was added to allow the complexation reaction taking place. The complex solution was used to impregnate the above solid of Ce—Al—O/γ-Al₂O₃-d, and the impregnated solid was baked, pyrolyzed and activated under the condition described in Example 3(2) to obtain the catalyst.

[0083] The catalyst was evaluated in the manner described in Example 2(3), and the CO conversions were determined to be 98% and 56%, respectively.

Example 6

[0084] For comparison with the present invention, a catalyst having no Al³⁺ ions in its active component, CuO/CeO₂/γ-Al₂O₃, was prepared.

[0085] (1) 8.71 ml of 2.01 mol/L aqueous solution of Ce(NO₃)₃ was mixed uniformly with 24.3 ml of water, then the mixed solution was used to impregnate 60 g of the support used in Example 1. The resulting impregnated support was baked, pyrolyzed and activated under the conditions described in Example 1(1) to obtain the solid of CeO₂/γ-Al₂O₃.

[0086] (2) 22.6 ml of 3.36 mol/L aqueous solution of Cu(NO₃)₂ was mixed uniformly with 10.4 ml of water, and the mixed solution was used to impregnate the above solid of CeO₂/γ-Al₂O₃. The impregnated solid was baked, pyrolyzed and activated under the condition described in Example 1(2) to obtain the catalyst CuO/CeO₂ /γ-Al₂O₃ (see FIG. 6).

[0087] The obtained catalyst was evaluated following the manner described in Example 2(3), and the CO conversions were determined to be 90% and 25%, respectively.

Example 7

[0088] (Riser Test)

[0089] The oil feed used for test was VGO from Xinjiang, China, the weight ratio of FCC catalyst to oil was 6.7 and the adding amount of residuum was 30% of the total weight of the feed. The sample 1# of the present invention was premixed with the FCC catalyst of LBO-16 manufactured by Catalyst Factory of Lanzhou Petrol Chemical Co., China. The adding amount of sample 1# was 3500 ppm. The adding amount of Pt combustion catalyst comprising 0.05% Pt was 3000 ppm. The contact time was 2.1 seconds, the reaction temperature was 500° C. The regeneration temperature was 680° C., TABLE 4 The result of riser test Yield NOx CO of LO Yield of total liquid Catalysts (ppm) (ppm) (%) products (%) Combustion catalyst 250 70 72.10 86.30 comprising Pt Sample 1 # 80 71 73.80 87.33

[0090] By comparing between aforesaid sample 1# and Pt catalyst, it demonstrated that (table 4) after using the additive of present invention, the yield of LO increased 1.70%, the yield of total liquid products increased 1.03%, the NOx reduced 68%. The CO combustion effects of these two catalysts were comparable.

Example 8

[0091] (Commercial-Scale)

[0092] The commercial-scale FCCU with side-by-side risers with annual capacity of 200 thousands tons and the LCS-7B type FCC catalyst manufactured by Catalyst Factory of Lanzhou Petrol Chemical Co., China were used. The oil feed was VGO, coke wax oil, or/and propane-deasphalted oil of 0# Xinjiang crude oil. The sample 1# present invention and combustion promoter comprising 0.05% Pt were tested respectively under the same conditions as the table below: TABLE 5 Commercial-scale operation conditions ald results Pt combustion Items catalyst Sample 1# Riser exit temp. (° C.) 464 464 Pre-heater exit temp. (° C.) 272 368 Recycle ratio 0.371 0.416 Catalyst to oil ratio 4.7 4.6 Combustion air rate (NM³/h 12000 12000 Bottom temp. of dense phase (° C.) 656 655 Top temp. of dilute phase (° C.) 689 688 Combustion promoter inventory 3000 3500 to FCC catalyst (ppm) Processing feedstock (T) 3616 4361 Production of products Sum of 7 days Sum of 8 days (productivity) Gasoline 1339 tons (37.03%) 1557 tons (35.70%) Diesel 1758 tons (48.62%) 2250 tons (51.59%) LPG 203 tons (5.61%0 213 tons (4.88%) Light oil 3097 tons (85.65%) 3807 tons (87.30%) Yield of total liquid products 3300 tons (91.26%) 4020 tons (92.18%) Octane number of gasoline 90.3 90.5 (RON) Olefins of gasoline (%) 65.5 63.4 Cetane number of Diesel 48 50 CO content in flue gas (ppm) 60 52 NOx content in flue gas (ppm) 350 99

[0093] Comparing between the Sample 1# and Pt combustion catalyst, using the additive of present invention increased the yield of LO by 1.65%, the yield of total liquid products by 0.92%, reduced NOx contents in flue gas by 71.7%. The CO content and temperitures difference of dense and dilute phases between the two catalysts are similar.

[0094] In addition to the foregoing disclosure, Applicant incorporates by reference the entirety of U.S. patent application Ser. No. 09/826,174 herein. 

1. A method of increasing the yields of light oil and total liquid products, promoting the combustion of CO and/or reducing the emission of NOx in petroleum refining FCC process, comprising the step of using a non-noble metal complex oxide catalyst as FCC additive which comprises Ce—Al complex oxide and Cu—Al complex oxide successively loaded on an aluminum oxide support, and the ratio of the loading weight is 0.02-0.10 for Ce—Al—O/Al₂O₃ and 0.05-0.15 for Cu—Al—O/Al₂O₃, respectively.
 2. A method according to claim 1 characterized in that the loading weight ratio is 0.04-0.06 for Ce—Al—O/Al₂O₃ and 0.08-0.11 for Cu—Al—O/Al₂O₃, respectively.
 3. A method according to claim 1 characterized in that said Ce—Al complex oxide covers a surface of the aluminum oxide support in the form of nanoparticles.
 4. A method according to claim 1 characterized in that a structure of said Ce—Al complex oxide can be presented by the general formula [I]: [Ce_(1−y)Al_(y][O) _(2−y/2)□_(y-2)]  [I] wherein y=0.05-0.30, □ represents the vacancy in the structure.
 5. A method according to claim 1 characterized in that said Cu—Al complex oxide is dispersed in cluster form on the aluminum oxide support, wherein the support is pre-covered with the particles of Ce—Al complex oxide.
 6. A method according to claim 1 characterized in that a structure of said Cu—Al complex oxide can be presented by the general formula [II]: [Cu_(1-3x/2)Al_(x)□_(x/2)]O   [II] wherein x=0.05-0.23, and □ represents the vacancy in the structure.
 7. A method according to claim 1 characterized in that said aluminum oxide support has a particle size of 10-100 μm.
 8. A method according to claim 1 characterized in that said aluminum oxide support is γ-Al₂O₃.
 9. An improved FCC catalyst which is obtained after treatment in the presence of a non-noble metal complex oxide catalyst as a FCC process additive which comprises Ce—Al complex oxide and Cu—Al complex oxide successively loaded on an aluminum oxide support, and the ratio of the loading weight is 0.02-0.10 for Ce—Al—O/Al₂O₃ and 0.05-0.15 for Cu—Al—O/Al₂O₃, respectively.
 10. A FCC catalyst according to claim 9 characterized in that said ratio of the loading weight is 0.04-0.06 for Ce—AlO/Al₂O₃ and 0.08-0.11 for Cu—Al—O/Al₂O₃, respectively.
 11. A FCC catalyst according to claim 9 characterized in that said Ce—Al complex oxide covers the surface of the aluminum oxide support in the form of nanoparticles.
 12. A FCC catalyst according to claim 9 characterized in that a structure of said Ce—Al complex oxide can be represented by the general formula [I]: [Ce_(1−y)Al_(y)][O_(2−y/2)□_(y/2)]  [I] Wherein y=0.05-0.30, □ represents the vacancy in the structure.
 13. A FCC catalyst according to claim 9 characterized in that said Cu—Al complex oxide is dispersed in cluster form on the aluminum oxide support, wherein the support is pre-covered with the particles of Ce—Al complex oxide.
 14. A FCC catalyst according to claim 9 characterized in that said Cu—Al complex oxide can be represented by the general formula [II]: [Cu_(1-3x/2)Al_(x)□_(x/2)]O   [II] Wherein x=0.05-0.23, □ represents the vacancy in the structure.
 15. A FCC catalyst according to claim 9 characterized in that said aluminum oxide support has a particle size of 10-100 μm.
 16. A FCC catalyst according to any one of claims 9 to 15 characterized in that said aluminum oxide support is γ-Al₂O₃. 